TOKYO—Japan's benchmark stock index rose Friday, but gains were limited on concern over ballooning government debt and uncertainty over the restructuring of struggling Japan Airlines Corp.

The Nikkei 225 index edged up 18.91 points, or 0.2 percent, to 10,257.56. During the week, the key stock index gained 2.4 percent. The broader Topix index slipped 0.3 percent to 900.95.

"Sentiment remained downbeat as investors were worried that the government may have to issue more bonds for the budget" in the coming fiscal year to March 2011, said Masashi Sato, market analyst at Mizuho Investors Securities Co. Ltd.

Prime Minister Yukio Hatoyama, who took office last month, pledged to cut wasteful government spending. But reports said the size of the next fiscal year's budget could hit a record 95 trillion yen ($1.2 trillion) with the issuance of massive deficit-covering bonds.

"Despite a weakening yen, which could boost export-linked shares, investors were reluctant to buy shares due to uncertainty over the new government's handling of the economy," Sato said.

The market was also unnerved by uncertainty over the restructuring of struggling Japan Airlines Corp., which has asked for a government bailout.

Among blue chips, Toyota Motor Corp., the world's biggest automaker, was unchanged at 3,620 yen.

Honda Motor Co. lost 1.1 percent to 2,780 yen. Nissan Motor Co. shed 0.7 percent to 672 yen. Sony Corp. added 1.9 percent to 2,650 yen.

Japan Airlines plunged 11 percent to 101 yen.

In currencies, the dollar was quoted at 90.92 yen in Tokyo late Friday,up from 89.53 yen in New York late Thursday. The euro stood at $1.4919 from $1.4952